The use of closure devices for selectively fastening storage containers, including plastic bags, is generally well known. Furthermore, the manufacture of closure devices made of plastic materials is generally well known to those skilled in the art, as demonstrated by the numerous patents in this area.
A particularly well-known use for closure devices is in connection with flexible storage containers, such as plastic bags. Such closure devices provide a convenient way to selectively close or seal the bag in order to retain matter therein.
Conventional closure devices typically utilize mating fastening strips or closure elements which are used to selectively seal the bag. With such closure devices, however, it is often difficult to determine whether the fastening strips are fully occluded. This problem is particularly acute when the fastening strips are relatively narrow. Accordingly, when such fastening strips are employed, there exists a reasonable likelihood that the closure device is at least partially open.
Such fastening strips are particularly difficult to manipulate or handle by individuals with limited manual dexterity. Thus, in order to assist these individuals and for ease of use by individuals with normal dexterity, the prior art has provided sliders for use in opening and closing the fastening strips, as disclosed, for example, in U.S. Pat. Nos. 4,199,845, 5,007,142, 5,007,143, 5,010,627, 5,020,194, 5,070,583, 5,283,932, 5,301,394, 5,426,830, 5,431,760, 5,442,838, and 5,448,808. Some of these sliders include a separator finger which extends at least partially between the fastening strips. When the slider is moved in the appropriate direction, the separator finger divides the fastening strips and opens the bag.
While the use of a slider certainly facilitates the opening and closing of interlocking fastening strips, there are certain difficulties involved with preventing movement of the slider beyond the ends of the fastening strips. In an attempt to rectify some of these difficulties, the prior art has provided end stops at either end of the fastening strips, as disclosed, for example, in U.S. Pat. Nos. 5,088,971, 5,131,121, and 5,405,478. Such end stops, however, suffer from assorted deficiencies including, for example, a relatively complex construction, a high relative cost, and a design which permits the slider to be pulled past the end stops and detached from the fastening strips if a sufficient pulling force is applied thereto. Specifically, in some prior art designs, a sufficient pulling force will cause the end stop to deflect or tear, and the slider will be able to move past the end stop and past the end of the fastening strips.